14.guyot: A seamount that had a coral reef growing on top of it, so that it is now flat-crested.

15.gyre: A large, circular flow pattern of ocean surface currents.

16.lagoon: A body of shallow seawater separated from the open ocean by a barrier island.

17.longshore current: The flow of water parallel to the shore just off a coast, because of the diagonal movement of waves toward the shore.

18.longshore drift: The movement of sediment laterally along a beach; it occurs when waves wash up a beach diagonally

19.oceanic plateau: A region of oceanic floor that is higher than surrounding areas; such regions have particularly thick oceanic crust and are relicts of submarine large igneous provinces.

20.offshore bar: A narrow ridge of sand that forms off the shore of a beach; some rise above sea level, and separate a lagoon on one side from the open ocean on the other.

21.organic coasts: A coast along which living organisms control landforms along the shore.

22.passive continental margin: A continental margin that is not a plate boundary.

23.pelagic sediment: Microscopic plankton shells and fine flakes of clay that settle out and accumulate on the deep-ocean floor.

24.reef bleaching: The death and loss of color of a coral reef.

25.sand spit: An area where the beach stretches out into open water across the mouth of a bay or estuary.

26.seamount: An isolated submarine mountain.

27.sea stack: An isolated tower of land just offshore, disconnected from the mainland by the collapse of a sea arch.

28.submarine canyons: A narrow, steep canyon that dissects a continental shelf and slope.

29.submergent coasts: A coast at which the land is sinking relative to sea level.

30.surface currents: An ocean current in the top 100 m of water.

31.swash: The upward surge of water that flows up a beach slope when breakers crash onto the shore.

32.thermohaline circulation: The rising and sinking of water driven by contrasts in water density, which is due in turn to differences in temperature and salinity; this circulation involves both surface and deep-water currents in the ocean.

33.tidal reach: The difference in sea level between high tide and low tide at a given point.

34.tide: The daily rising or falling of sea level at a given point on the Earth.

35.tide-generating force: The force, caused in part by the gravitational attraction of the Sun and Moon and in part by the centrifugal force created by the Earth's spin, that generates tides.

36.wave base: The depth, approximately equal in distance to half a wavelength in a body of water, beneath which there is no wave movement.

37.wave-cut bench (platform): A platform of rock, cut by wave erosion, at the low-tide line that was left behind a retreating cliff.

38.wave-cut notch: A notch in a coastal cliff cut out by wave erosion.

39.wave refraction: The bending of waves as they approach a shore so that their crests make no more than a 5° angle with the shoreline.